Spark plug



Nov. 114, 1939. c, s n- 2,179,801

SPARK PLUG I Filed April 7, 1939 Fi l m. a 1i llgi fnue for:

Mid/M tented Nov. 14, 1939 UNITED STATES PATENT OFFICE- SPARK PLUG Charles Smith, St. Louis, Mo., assignor of onefourth to John H. '.l heis-, Pacific, M0.

Application April 7, 1939, Serial No. 266,566

7 Claims. .(Cl. 123 169) This invention relates to improvements in spark plugs and has for its object a plug constructed preferably of aluminum alloy with re-' movable insulated cores and electrodes which members may be replaced in the event one or both should become inoperative.

A further object of this invention is to construct the lower end of the shell with a ring comprising a. spark producing element which becomes instantly heated through the explosion taking place in the engine cylinder making the plug more eflicient and productive.

Another object is to provide a plug having one of its electrode supporting members arranged to freely move within the casing so that contact is made during each compression of the cylinder, and its spark producing end move around to create a spark at any point with the ring formed on the lower end of the casing.

The electrodes in this invention are constructed of a high grade of chromel alloy, the movable electrode having on its upper end a contact cup, while at its lower end is formed a spark producing point positioned to move freely 5 up and down as well as around so that a spark will be created at any point with the ring.

Another object of the invention is the general arrangement," constiiiction and combination of parts as will be fully hereinafter de- 0 scribed and set forth in the claims.

' This invention is an improvement over my former patent issued to me on January 3, 1939, and numbered 2,142,383.

Figure 1 is a side elevation of my complete in- 35 vention.

Figure 2 is a vertical central sectional view of the same.

Figure 3 isa, detail perspective View 01' the lower part of the plug showing the vital part of 40 my improvement.

Figure 4 is a detail view of the lower end of the plug showing one side thereof.

Figure 5 is a vertical central sectional view of the same with the electrode removed.

45 Figure 6 is a vertical central sectional view showing the plug turned one quarter around with its electrode in operative position.

In the general construction of my invention I provide an outer casing I the same being pref- 50 erably constructed of chromel alloy; it is provided with the usual threads 8 by which the plug is attached to the engine block; it is also provided with a hex enlargement 9 to which a wrench may be applied for inserting or remov- 55 ing the same from the block, and on its upper end electrode I5, its lower end provided with an enlargement I6 projecting into a cavity l'l formed in the lower end of the insulating member; the 5 upper end of the electrode is screwthreaded and over which is applied a nut l8 so shaped as to fit into a tapered cavity l9 coated with porcelain cement to prevent leakage and likewise to retain the electrode in rigid position. 20

Inthe casing is 'formed a bore I9!* 01 smaller diameter than the cavity l2; it is provided with a bevel 2|! then terminating into a still narrower bore 2|. In this-formation of bore is seated a movable insulating member 22, its upper 'end formed to project into .and move within the cavity ll of the upper insulating member. In this insulating member is positioned an electrode 23, its upper end provided with a cap-24, its uppersurface provided with a cavity of a shape to correspond with the outer contour of the electrode enlargement It so that when contacting therewith will complete electrical contact. I

The lower end of the insulating member 22 is tapered as shown and in its lower end is a cavity 25 which provides for the insertion of the collar 26 carried by the electrode 23. By this arrangement andthe cap 24 the electrode is rigidly fixed in the insulating member. The bottom end of the electrode is formed into a spark forming o arm or pit 21. It registers in proper degree with a ring 28 located at the extreme lower end of the casing and is supported to said casing by arms 29 and is split at two sides as indicated by the numeral 30.

By the formation and arrangement of this ring it permits that portion to become instantly heated by the explosion which takes place in the cylinder and consequently produces an instant spark between the ring and spark producing point of the electrode, and during each compression in the cylinder the lower electrode and its supporting member will elevatemaking contact with the upper electrode. The movement is comparailvely small so as not to remove the spark forming point too far away from the ring, yet during the firing process, the spark forming point of the electrode may assume any position horizontally around the inside of the ring, so that no matter where the point may be located a spark will be created.

By this arrangement no carbon will form within the plug, and should for any reason any one of the inner parts become ineffective, they can be replaced without discarding the entire plug.

The essential feature of the invention is the formation of the ring on the lower part of the casing, as the ring when it becomes heated through the explosions which take place in the cylinder functions through expansion and contraction bringing the ring nearer to or farther away from the firing point of the electrode, this expansion and contraction is made possible by the splitting of the ring as shown.

Through this expansion and contraction a better result is obtained as the gap between the firing point and ring is automatically regulated by the heat condition, thus the spark created is at all times uniform and functional.

I claim:

1. A spark plug of the character described comprising a casing, an upper rigid and a lower movable insulating core mounted therein, electrodes carried by said insulating cores, a ring formed on the bottom end of the casing and conveniently spaced between the ring and terminal of the casing, and a spark forming point formed on the lower end of the movable electrode to form a spark between the point and ring, and to move freely vertically as well as horizontally.

2. A spark plug of the character described comprising a casing its interior provided with a cavity, a pair of insulating cores positioned in the cavity, the upper core being held rigid, the lower core permitted to freely move therein, electrodes positioned in the cores and arranged to make contact bythe vertical movement of the lower core, a ring formed on the lower end. of the casing and suitably spaced, the interior of said ring being beveled, and a firing point formed on the lower electrode to create a spark between it and the ring, and freely move vertically and horizontally with the electrode.

3. A spark plug comprising a casing, a ring formed at the lower end thereof, said ring spaced therefrom by arms, said ring being split at two points, a rigid insulating core positioned in top of the casing, a movable insulating core positioned in the bottom of said casing, electrodes carried by the insulating cores and so arranged as to make contact when brought together, a firing point formed on the lower electrode and to create a spark between the point so and ring.

4. A spark plug comprising a casing the lower threaded end being cut away so as to form a ring extension, a ring formed by such construction and spaced by arms, the interior of said ring being beveled, a stationary and a movable electrode located in the casing and insulated therefrom, a firing point formed on the lower end of the movable electrode and freely movable and to create a spark between it and the ring during the compression of the motor.

5. A spark plug of the character described comprising a casing, a ring formed at the lower end of said casing and reasonably spaced therefrom by posts, said ring being of thinner material and becoming instantly heated by the explosions taking place within the cylinder of a motor, a movable electrode positioned in the caspart of said cavity, a movable core seated in the lower part of the cavity, electrodes of chromel alloy carried by the cores, means provided whereby the electrodes may contact when the lower core is elevated, a ring formed on the lower end oi said casing and suitably spaced, and a firing point formed on the lower movable electrode and arranged to create a spark between it and the ring when connection is made between the electrodes.

7. A spark plug comprising a casing the same having an interior bore of three varying widths, an insulating member seated in the upper and larger part of the bore, a cap covering and retaining the core in rigid position therein, an electrode carried by said core and an enlargement formed on the bottom of said electrode and extending into a cavity formed in the insulating member, a second insulating member positioned in the second largest part of the bore and having a tapered extension, an electrode carried by said insulating member, a cup formed on the upper end thereof and'provided with a cavity to correspond with the contour of the enlargement of the upper electrode, a firing point formed on the lower endof the electrode, a ring formed on the extreme lower end of the casing and of thinner material and conveniently spaced therefrom by slits, the movement of the electrode for functioning being of a very slight degree and to create a spark between it and the ring in no matter what position it may be horizontally.

CHARLES SMITH. 

